Stout with weak fermentation

[jbrewkeggin]

Hi,

A few weeks ago I pitched some liquid yeast into a batch of stout. I took a gravity reading with a "calibrated" refractometer, which read around 1.067. I used a small blowoff tube, which didn't appear to show any sign of a vigorous fermentation. After about a week, I still didn't see any bubbling, but I did peak inside my bucket, and I saw a layer of krausen. I let the batch sit for another week, and took another gravity reading. My refractometer read 1.029, and a triple scale hydrometer read 1.040.

I found out that my yeast was slightly expired, so my lhbs gave me another free tube. At this point I'm wondering if I should re-aerate my wort a little and pitch this new tube. This is the first time I've experienced anything other than a healthy fermentation, so I'm not really sure if I should just go ahead and keg or not. Thanks for any suggestions.

 

[kh54s10]

Do not aerate the partially fermented beer. That would give you oxidation flavors of wet cardboard. Slightly expired should not have caused a stall though I guess it could. But you should have made a starter with the yeast. I do a starter for any beer with an OG of 1.040 or higher.

Your refractometer will not give you a useful reading with the presence of alcohol. Use the hydrometer. Take another reading, make sure the temperature of the sample is in the range of the hydrometer. If it is still high make a starter with the new yeast then pitch it and hope for the best.

 

[day_trippr]

I would also be reticent to aerate a batch so late in the game.
If successive hydro checks don't show any drop in a week I'd grow up a big starter and pitch it at high krausen...

Cheers!

 

[RM-MN]

Take another hydrometer reading. With fermented beer the hydrometer should always read lower than a refractometer as the alcohol skews the reading of the refractometer.

 

[eadavis80]

1.040 is pretty high. What temp did you mash at? Any unfermentables in the recipe? What was the yeast strain? I had a stout that stopped at 1.020. Maybe my thermometer is off 'cause I believe I mashed at 152 which should have left plenty of fermentables. I used Wyeast 1084 for that one. I would let it sit another week and maybe throw some Safale 04 at it to see if it can eat up anything left. I tried that, but my gravity didn't change, but at least I know it's as low as it will go. Good luck.

 

[jbrewkeggin]

Do not aerate the partially fermented beer. That would give you oxidation flavors of wet cardboard. Slightly expired should not have caused a stall though I guess it could. But you should have made a starter with the yeast. I do a starter for any beer with an OG of 1.040 or higher.

Your refractometer will not give you a useful reading with the presence of alcohol. Use the hydrometer. Take another reading, make sure the temperature of the sample is in the range of the hydrometer. If it is still high make a starter with the new yeast then pitch it and hope for the best.

I'll give this a shot. Thanks very much for the advice.

 

[jbrewkeggin]

1.040 is pretty high. What temp did you mash at? Any unfermentables in the recipe? What was the yeast strain? I had a stout that stopped at 1.020. Maybe my thermometer is off 'cause I believe I mashed at 152 which should have left plenty of fermentables. I used Wyeast 1084 for that one. I would let it sit another week and maybe throw some Safale 04 at it to see if it can eat up anything left. I tried that, but my gravity didn't change, but at least I know it's as low as it will go. Good luck.

I mashed at around 157-158 degrees. The only unusual thing I dropped in the recipe was a small bag of paradise seeds, but I don't think that would be the issue. I used White Labs WLP060 American Ale Yeast the first time around. Thanks for the help!

 

[kh54s10]

IMO, 158 is really high. I do stouts and porters at 154. It will make your beer more sweet and it will stop at a higher FG. But it should still be well lower than 1.040

 

[Kee]

Yes, 158 is right on the edge. I mashed that high one time and the beer finished 8-10 gravity points higher than normal.

How clear is the beer? If you still have yeast in suspension (and your fermentation temps are in range), you may have a chance but if not I'd take the above advice about making a starter. Personally, I'd pitch the whole starter at high krausen.